The present disclosure relates to a computer-implemented method for verification of a layout of an integrated circuit according to a design intent with a selected manufacturing process. The disclosure further relates to a method for providing verified layout data. The disclosure further relates to a method of manufacturing a mask. The disclosure further relates to a method of manufacturing an integrated circuit. The disclosure further relates to a computer system for verification of a layout of an integrated circuit. The disclosure further relates to a non-transitory computer storage medium.
Designs of integrated circuits are typically obtained using computer aided design (CAD) software. The CAD software may process and store layout data that represents the integrated circuit. The layout data may comprise circuit parts defined e.g. by their edge coordinates. When a design is finished, it can be transferred to one or more masks for manufacturing the integrated circuit or layers thereof.
In order to verify that an integrated circuit design is compliant with manufacturing conditions, i.e. to predict whether a functioning integrated circuit can be reproducibly manufactured from a designed layout, the CAD software may use a process known as “design rule checking” (DRC). In this process, the compliance of a designed layout or parts thereof may be quantified e.g. as one or more parameters that indicate whether a layout is acceptable or not and/or indicate a degree of compliance.
The task of verification of an integrated circuit may be divided into sub tasks wherein critical regions of the integrated circuit are verified. A critical region may be defined as a region comprising critical points or hotspots wherein a local topology of the circuit parts provides an essential functionality of the circuit. These terms are known e.g. from U.S. Pat. No. 8,041,103. In one example a functioning of the circuit may depend on an overlap between two circuit parts to establish an electrical interconnection there between. In another example, a functioning of the circuit may depend on there being sufficient spacing between two circuit parts to prevent short-circuit or other type of interference between the circuit parts.
Determining whether a layout is compliant may depend on limitations of the manufacturing process for producing the integrated circuit. For example, the manufactured layout may be influenced by the accuracy of alignment between different layers, e.g. the manufactured circuit parts may be relatively shifted compared to the original design. To take this limitation into account when the design intent is to form an electrical connection, U.S. Pat. No. 6,275,971 describes a method for checking integrated circuit layout design files. Unfortunately the method may not be suitable for all via geometries. Furthermore, there are also other limitations of the manufacturing process besides alignment that need to be considered.
Most notably, the manufacturing process may be limited by a minimal spot size or critical dimension that can be reproducibly manufactured. This limitation may cause e.g. a rounding of corners and edges of the circuit parts compared to the original polygon patterns. Also, circuit parts may be smaller, larger or otherwise deformed compared to the original design.
In current state of the art, design rules for determining compliance are typically described as limitations on distances between shapes, and/or or parts of shapes such as corners or edges. In order to check limitations that hold in two dimensions (e.g. on a silicon substrate surface), combinations of distance checks can be used. For instance a check can be made if a distance between a first edge of a first circuit part and a second edge of a second circuit part has a large enough value in either the horizontal or the vertical direction.
Unfortunately, the current design rule checking can become increasingly complicated when physical manufacturing conditions are taken into account. For example, when a design contains two overlapping square circuit parts, the corresponding set of design rules may need to consider that the shapes, e.g. corners, of said parts may be substantially rounded in the corresponding manufactured circuit. This may lead to a cumulative set of conditions wherein combined distances with respect to the rounded shape are checked.
There is a need for a simpler method of design rule checking taking into account physical manufacturing conditions and widely applicable to various design intents and circuit shapes.